Earlywood and latewood in wood pulp, and earlywood and latewood proportion, beating beating with the same conditions, the resulting pulp qualities are different, latewood fibers long and thick cell walls and hard, born wall from being damaged easily, beating these fibers were cut off, water swelling and comparison of fibrillating difficulties. Therefore, the proportion of late wood pulp in secondary refining, especially when slow beating should be lower than the pressure, the higher the concentration, taking successive knife or beating gradually narrowing the knife from the method. Early wood fiber is thin, fiber is soft, beating easy separation into individual fibers, beating easy.